1. Field of the Invention
The present invention relates to an apparatus and method for unifying multiple radio frequency identification (RFID) tags as a single encrypted value and a user privacy protection method using the single value, more particularly, to an apparatus and method for unifying identifiers of multiple RFID tags that belong to a user and encrypting the unified identifiers using a public key by which the user is recognized to have a single encrypted radio frequency identifier, and for protecting privacy of the user that owns the multiple RFID tags.
2. Description of the Related Art
Conventional user privacy protection methods are classified into kill tag methods and blocker tag methods that prevent radio frequency identification (RFID) of a user from being read. The kill tag methods inactivate an RFID tag including a password when the same password as the password of the RFID tag and a kill command are received from a reader. The RFID tag including a circuit that could be shorted is dead when the circuit is short. There is no method to restore the dead RFID tag. The blocker tag methods have a different operating principle according to collision avoidance systems. In a binary tree-walking system, the user owns a separate blocker tag that consistently responds yes or no to all inquiry messages of the reader so that the reader is confused due to actual information of the user. In a slot aloha system, the reader is confused due to a separate blocker tag that responds to all slots and causes collision. Also, unlike the blocker tag methods, a method of encrypting RFID prevents an eavesdropper from exactly understanding information.
However, when an authentic reader attempts to read belongings of the user, for example, an authorized legal institution having a search right such as the Exit and Entry Control Bureau searches for belongings of a passenger, the authentic reader cannot find RFIDs of the belongings of the passenger using the kill and blocker tag methods. Also, although the eavesdropper reads an encrypted RFID and cannot exactly understand content included therein, the eavesdropper can acquire the number of RFID tags owned by the user, and use the encrypted value of RFID to track a movement route of the user. If valuables, money, securities, etc. use the RFID encrypting method, the number of RFID tags of the valuables, money, securities, etc. is exposed and the RFID tags are illegally tracked, which may infringe user's privacy.